This research project proposes to analyze the immunoregulatory mechanisms active in the spontaneous suppressive modulation of the granulomatous hypersensitivity response which occurs at the chronic phase of murine schistosomiasis. Our main objective is to analyze the immune system of the infected mice, and to manipulate the immune response in such a fashion, that modulation should be operative concurrently with the evolution of the granulomatous reaction. To this end we'll employ repeated transfers of suppressor lymphocytes, will induce high levels of specific humoral antibodies, and will examine the effect of granuloma macrophages on the immune response. The research objectives are divided into 4 areas: 1. The functional characterization of fractionated T and B lymphocytes of infected mice. Lymphoid populations will be fractionated by adherence, velocity sedimentation and the use of various alloantisera. (Anti-Thy 1.2, anti-Ia, anti-Ly, etc.). Effector, helper and suppressor functions of T lymphocyte subsets will be characterized. 2. Regulation of the immunopathology of infected mice by adoptively transferred lymphocytes. Enriched subpopulations of T lymphocytes and B cells of modulated infected and appropriately sensitized donors will be transferred to recipients and the modulation of the granulomatous, and general cell-mediated responses as well as host morbidity will be assessed. 3. Regulation of the immunopathology of infected mice induced by elevated humoral immune responses. High antibody levels to egg antigens will be induced by various protocols of immunization and the granulomatous reactions as well as host morbidity will be assessed in the infected mice. Additionally, the effect of overt suppression of the granulomatous response on liver and kidney pathology of the infected mice will be evaluated. 4. The role of the macrophages isolated from granulomas in egg antigen sequestration, antigen-antibody complex retention, the induction, elicitation and the suppression of the specific immune response will be investigated.